1. Field of the Invention
The invention relates to a plunger-latch mechanism for an optical disk drive, and particularly, to a plunger-latch mechanism that requires reduced electric power to open the optical disk drive, and keeps a tray of the optical disk drive stable while the optical disk drive is in a closed state.
2. Description of the Related Art
A tray control unit of a conventional optical disk drive including a tray 4 and a casing 1 is controlled by a latch mechanism. This latch mechanism usually includes a solenoid 7, a compression spring 8, a latch 10, and a manually actuated slider 10a. The solenoid 7 generates a magnetic force sufficient to overcome a resilient force of the spring, so that the latch 10 is pushed away from a wedge 13 of the latch 10 to slidably separate the tray 4 from the casing 1. When the tray 4 is outwardly pulled out to an outmost position from the optical disk drive and after an optical disk has been placed thereon, the tray 4 then is retracted inside the optical disk drive. Information then is read or written on the optical disk via a read/write head 3.
Conventionally, a solenoid type latch mechanism, including the solenoid 7, the compression spring 8, the latch 10 and the manually actuated slider 10a, is mounted at a side of the tray 4. When the latch 10 is in a closed state, the solenoid 7 has no magnetic flux. At this time, the locking force comes from the resilient force. As illustrated, the latch 10 and the wedge 13 are locked by the compression spring 8 between a connecting rod 7a of the solenoid 7 and the latch 10. The wedge 13 is mounted on the casing 1.
If the latch 10 is to be opened, the magnetic force generated after the solenoid 7 is electrified must be sufficient to resist to the resilient force of the compression spring 8, as illustrated in FIG. 3, to push the latch 10 away from the wedge 13. However, the conventional latch mechanism of the optical disk drive has the following disadvantages:
1. Low electric current loss is an important factor in designing the optical disk drive, especially a thin optical disk drive used within a laptop. The conventional solenoid type latch mechanism requires a sufficiently large electric current to resist the resilient force of the compression spring 8, which results in considerable consumption of electric power.
2. The conventional solenoid type latch mechanism has a locking force that is usually not sufficient to endure shock during transportation, because the latch 10 is not firmly fastened to the wedge 13.